The invention concerns a high frequency shielded duct with a shielded cable running through the wall of an electrically conductive housing for electrical and electronic components.
The high frequency shielded duct finds application in high frequency shielded housings and cabinets of industrial electronics, in which elements and modules are accommodated. These elements and modules are sensitive to electromagnetic interfering radiation and their components can also produce interfering radiation, which must not be allowed to penetrate outward.
Increasingly components are built into housings and cabinets of electrical engineering or rather electronics. These housings necessitate an increasingly smaller noise margin due to ever lowering voltage levels and higher switching frequencies. With shielded systems it is well known that the cable ducts are the critical points at which high frequency interference currents on the cable shields are often not sufficiently drawn off and thereby the put into question the entire complex shielding of the housing or cabinet.
There are different well-known high frequency shielded ducts for use with shielded unfinished single cables (those without a plug connected), which cause a perfect electrical contacting of the cable's shield with the high frequency shielded duct. Common to all of these ducts is the lavish cost of assembly for bringing the cable into the duct. It is particularly unfavorable that the mounting of the plug connectors to the cable ends is possible often only after final assembly of the duct at the housing or cabinet. This means that additional work is expended at the place of assembly. Thus stripping, splicing, attaching the fastening piece, and soldering must be executed before the cabinet or the housing can be set up and attached to its workstation. In an electrically shielded connector with a metallic housing, according to DE 40 13 963, after removing the cable sheath, a sleeve must be put on over the cable shield. The opened shield is then brought down and fastened to the outside diameter of the case. In another design of ducts the opened cable shield is dragged through a metal pan filled with metal balls, such that the shield makes contact with the wall of the metal housing over the balls.
It is also well known, high frequency shielded cable entry housing, to fasten an assembly disk to the inside of the housing wall next to an opening for the cable passage. The duct channels are intended to have tension relievers for the cables, which are fastened to the mounting plate. The installation and attachment of the cables is however time-consuming; already made cables complete with plugs cannot be pulled through the channels (DE 40 13 886).
Further known is a switch cabinet with a high frequency shielded duct for cable consisting of two, inserted floor plates arranged at the base. These plates possess sealing strips of a flexible, electrically conductive material at bent edgings between which the cables, with their bare metal shield, are held. The assembly of the two floor plates and the use of cables is pedantic however (DE 196 04 219).
The task of the invention lies therein, to develop a high frequency shielded duct for shielded cables in such a way that a single or several cables including their plug connectors can be passed through the wall of an electrically conductive housing with the least assembly expenditure.